The rainfall distribution this monsoon looks as patchy as ever, though with some unexpected patterns.
The seasonal outlook provided by the India Meteorological Department (IMD) predicted normal to above-normal rainfall based on the expectation that a La Niña is likely.
La Niña, however, appears to be playing truant.
After onset, the northward movement of the monsoon trough seemed to be quite rapid.
But then the trough stalled and produced a fairly dry June over large swathes of the country.
The entire Western Ghats received below-normal rainfall into July.
An unusual pattern of excess rain stretching from south to north persists to this day, with dry patches over large parts of Uttar Pradesh, Bihar, Jharkhand, and Odisha, as well as north -western India into Jammu and Kashmir.
However, the convenience of using the ‘all-India monsoon rainfall’ index for seasonal outlooks — as the IMD does — is undermined by the uncertainty India’s farmers face at the local level
Our forecasts of rain days or weeks ahead of a given date are getting better, but they concomitantly increase the demand for, and value of, even more accurate and hyperlocal forecasts.
This demand is not only from farmers but also from water managers and energy companies, among others.
We need a broader perspective of the monsoon circulation to help understand where the limitations exist and how they can be resolved.
Limitations of current forecasting methods
As hard as the IMD and its labs are working to improve their monsoon forecasting abilities at all timescales, their efforts are also undermined by a lack of rainfall and other weather data over parts of the subcontinent beyond India.
Satellites can help to some extent, but the amount of data available in near real-time to initiate forecasts is often quite inadequate.
These rainfall models are global for most subcontinent-scale forecasts, even though the IMD also develops regional model forecasts at the level of cities, and at the national scale
The global models ingest data about the oceans and the planetary atmosphere to initiate forecasts, and the volume of data can appear to be large and adequate — but this is often not the case
Way forward
At this point, we need a few important steps to reach the next level in forecast accuracy.
This is also essential to sustain continuous economic growth for India, especially in terms of food, water, and energy security.
In fact, even our national security depends heavily on weather and climate forecasts — for India as well as for the country’s more climate-vulnerable neighbours.
Debilitating natural disasters can quickly turn into national security concerns, especially with some neighbours having to seek aid from non-allies.
India does share its forecasts with some countries, but it may benefit more by extending this strategy to also establish a broad network to monitor weather and climate across the subcontinent.
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